U.S. patent number RE31,088 [Application Number 05/904,941] was granted by the patent office on 1982-11-23 for process for the manufacture of unsaturated aldehydes and acids from the corresponding olefins.
This patent grant is currently assigned to Standard Oil Company. Invention is credited to Robert K. Grasselli, Ernest C. Milberger, Dev D. Suresh.
United States Patent |
RE31,088 |
Grasselli , et al. |
November 23, 1982 |
Process for the manufacture of unsaturated aldehydes and acids from
the corresponding olefins
Abstract
A process for the catalytic oxidation of olefins to unsaturated
aldehydes and acids and the ammoxidation of olefins to unsaturated
nitriles in which the catalyst comprises a promoted, reduced,
antimony oxidemolybdenum oxide-containing catalyst.
Inventors: |
Grasselli; Robert K. (Chagrin
Falls, OH), Suresh; Dev D. (Macedonia, OH), Milberger;
Ernest C. (Solon, OH) |
Assignee: |
Standard Oil Company
(OH)
|
Family
ID: |
27397426 |
Appl.
No.: |
05/904,941 |
Filed: |
May 11, 1978 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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224967 |
Feb 9, 1972 |
3892794 |
|
|
Reissue of: |
390094 |
Aug 20, 1973 |
03956378 |
May 11, 1976 |
|
|
Current U.S.
Class: |
562/535 |
Current CPC
Class: |
B01J
23/28 (20130101); B01J 23/30 (20130101); B01J
23/31 (20130101); B01J 23/32 (20130101); B01J
23/8875 (20130101); B01J 23/8876 (20130101); B01J
23/8878 (20130101); B01J 27/00 (20130101); B01J
27/0576 (20130101); C07C 45/34 (20130101); C07C
45/35 (20130101); C07C 51/252 (20130101); C07C
253/26 (20130101); C07D 307/79 (20130101); C07D
307/80 (20130101); C07D 307/82 (20130101); C07D
307/83 (20130101); C07D 307/92 (20130101); C07D
333/60 (20130101); C07D 333/68 (20130101); D06L
4/636 (20170101); C07C 45/35 (20130101); C07C
47/22 (20130101); C07C 51/252 (20130101); C07C
57/04 (20130101); C07C 253/26 (20130101); C07C
255/08 (20130101); B01J 2523/00 (20130101); Y02P
20/52 (20151101); B01J 2523/00 (20130101); B01J
2523/53 (20130101); B01J 2523/68 (20130101); B01J
2523/00 (20130101); B01J 2523/31 (20130101); B01J
2523/53 (20130101); B01J 2523/68 (20130101); B01J
2523/00 (20130101); B01J 2523/53 (20130101); B01J
2523/68 (20130101); B01J 2523/847 (20130101); B01J
2523/00 (20130101); B01J 2523/53 (20130101); B01J
2523/62 (20130101); B01J 2523/68 (20130101); B01J
2523/00 (20130101); B01J 2523/53 (20130101); B01J
2523/68 (20130101); B01J 2523/69 (20130101); B01J
2523/00 (20130101); B01J 2523/53 (20130101); B01J
2523/54 (20130101); B01J 2523/68 (20130101); B01J
2523/00 (20130101); B01J 2523/51 (20130101); B01J
2523/53 (20130101); B01J 2523/68 (20130101); B01J
2523/00 (20130101); B01J 2523/305 (20130101); B01J
2523/53 (20130101); B01J 2523/68 (20130101); B01J
2523/00 (20130101); B01J 2523/53 (20130101); B01J
2523/64 (20130101); B01J 2523/68 (20130101); B01J
2523/00 (20130101); B01J 2523/53 (20130101); B01J
2523/64 (20130101); B01J 2523/68 (20130101); B01J
2523/69 (20130101); B01J 2523/00 (20130101); B01J
2523/53 (20130101); B01J 2523/68 (20130101); B01J
2523/72 (20130101); B01J 2523/00 (20130101); B01J
2523/17 (20130101); B01J 2523/53 (20130101); B01J
2523/68 (20130101); B01J 2523/00 (20130101); B01J
2523/44 (20130101); B01J 2523/53 (20130101); B01J
2523/68 (20130101); B01J 2523/00 (20130101); B01J
2523/53 (20130101); B01J 2523/68 (20130101); B01J
2523/74 (20130101); B01J 2523/00 (20130101); B01J
2523/43 (20130101); B01J 2523/53 (20130101); B01J
2523/68 (20130101); B01J 2523/00 (20130101); B01J
2523/43 (20130101); B01J 2523/53 (20130101); B01J
2523/64 (20130101); B01J 2523/68 (20130101); B01J
2523/00 (20130101); B01J 2523/53 (20130101); B01J
2523/67 (20130101); B01J 2523/68 (20130101); B01J
2523/00 (20130101); B01J 2523/47 (20130101); B01J
2523/53 (20130101); B01J 2523/68 (20130101); B01J
2523/00 (20130101); B01J 2523/53 (20130101); B01J
2523/68 (20130101); B01J 2523/842 (20130101); B01J
2523/00 (20130101); B01J 2523/53 (20130101); B01J
2523/64 (20130101); B01J 2523/68 (20130101); B01J
2523/842 (20130101); B01J 2523/00 (20130101); B01J
2523/397 (20130101); B01J 2523/53 (20130101); B01J
2523/68 (20130101) |
Current International
Class: |
B01J
23/31 (20060101); B01J 23/32 (20060101); B01J
23/30 (20060101); B01J 23/28 (20060101); B01J
23/16 (20060101); B01J 27/057 (20060101); B01J
23/887 (20060101); B01J 27/00 (20060101); B01J
23/76 (20060101); B01J 23/88 (20060101); C07D
307/82 (20060101); C07D 307/83 (20060101); C07C
45/00 (20060101); C07D 307/80 (20060101); C07D
307/79 (20060101); C07D 307/00 (20060101); C07C
51/16 (20060101); C07C 51/25 (20060101); C07C
45/35 (20060101); C07D 333/68 (20060101); C07D
307/92 (20060101); C07D 333/60 (20060101); C07D
333/00 (20060101); D06L 3/12 (20060101); D06L
3/00 (20060101); C07C 051/16 () |
Field of
Search: |
;562/535 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Killos; Paul J.
Attorney, Agent or Firm: Untener; David J. Knudsen; Herbert
D. Evans; Larry W.
Parent Case Text
This is a division of application Ser. No. 224,967, filed Feb. 9,
1972, now U.S. Pat. No. 3,892,794.
Claims
We claim:
1. A process for the oxidation of propylene and isobutylene to form
the corresponding unsaturated aldehydes and unsaturated acids
comprising contacting in the vapor phase at a temperature within
the range of from about 250.degree. to about 600.degree. C. a
mixture of a molecular oxygen-containing gas and either propylene
or isobutylene, or mixtures thereof, in a molar ratio of oxygen to
olefin within the range from about 0.5 to 10, in the presence of a
promoted, reduced, antimony oxide-molybdenum oxide-containing
catalyst wherein the catalyst is prepared by combining the
following components in any order:
a. an aqueous slurry of molybdenum trioxide;
b. a reducing agent selected from the group consisting of finely
divided metal, sulfur, sulfur dioxide, hydrogen sulfide, hydrazine,
hydrate, ammonia, hydroxylamine and an organic reducing agent
capable of reducing at least some of the molybdenum to a valence
state below +6 in a ratio of from about 0.0001 to 0.2 moles of the
reducing agent per mole of molybdenum;
c. antimony oxide in a ratio of from about 0.1 to 9 moles of
antimony oxide per mole of molybdenum; and
d. at least one promoter element in the form of a non-oxidizing
compound selected from the group consisting of tellurium, tungsten,
titanium, manganese, nickel, iron, copper, lead, rhenium, bismuth,
tin, uranium, chromium, phosphorus and boron, said promoter element
being added in a ratio of from about 0.0001 to 10 moles of promoter
element per mole of molybdenum.
2. The process in claim 1 wherein the finely divided metal in
component (b) in the catalyst preparation is selected from the
group consisting of molybdenum, tungsten, aluminum and nickel.
3. The process in claim 2 wherein the catalyst components are
combined in the following order:
a. molybdenum trioxide is reacted with the reducing agent;
b. antimony trioxide is added to the reaction mixture of (a);
and
c. the promoter element in the form of a non-oxidizing compound is
subsequently added to the reaction mixture of (b). .Iadd. 4. A
process for the production of methacrylic acid by the oxidation of
methacrolein with molecular oxygen in the vapor phase at a reaction
temperature of about 200.degree. C. to about 500.degree. C. in the
presence of a promoted, reduced, antimony oxide-molybdenum oxide
containing catalyst wherein the catalyst is prepared by combining
the following components in any order:
a. an aqueous slurry of molybdenum trioxide;
b. a reducing agent selected from the group consisting of a finely
divided metal, sulfur, sulfur dioxide, hydrogen sulfide, hydrazine
hydrate, ammonia, hydroxylamine, and an organic reducing agent
capable of reducing at least some of the molybdenum to a valence
state below +6 in a ratio of from about 0.0001 to 0.2 mole of the
reducing per mole of molybdenum;
c. antimony oxide in a ratio of from about 0.01 to 9 moles of
antimony oxide per mole of molybdenum; and
d. at least one promoter element in the form of a non-oxidizing
compound selected from the group consisting of tellurium, tungsten,
titanium, manganese, nickel, iron, cobalt, lead, rhenium, bismuth,
tin, uranium, chromium, phosphorus and boron, said promoter element
being added in a ratio of from about 0.0001 to 1.0 moles of
promoter element per mole of molybdenum. .Iaddend..Iadd. 5. The
process of claim 4 wherein the finely divided metal in component
(b) in the catalyst preparation is selected from the group
consisting of molybdenum, tungsten, aluminum and nickel. .Iaddend.
.Iadd. 6. The process of claim 5 wherein the promoter element is
phosphorus. .Iaddend..Iadd. 7. The process of claim 6 wherein
catalyst is of the formula P.sub.0.01 [Sb.sub.2 Mo.sub.3 O.sub.x
+Mo.degree..sub.0.06 ]. .Iaddend..Iadd. 8. The process of claim 5
wherein the finely divided metal in component (b) in the catalyst
preparation is molybdenum. .Iaddend..Iadd. 9. The process of claim
5 wherein the catalyst components are combined in the following
order:
a. molybdenum trioxide is reacted with a reducing agent;
b. antimony trioxide is added to the reaction mixture of (a);
and
c. the promoter element in the form of a non-oxidizing compound is
subsequently added to the reaction mixture of (b). .Iaddend..Iadd.
10. A process for the production of methacrylic acid by the
oxidation of methacrolein with molecular oxygen in the vapor phase
at a reaction temperature of about 200.degree. C. to about
500.degree. C. in the presence of a reduced, antimony
oxide-molybdenum oxide containing catalyst wherein the catalyst is
prepared by combining the following components in any order:
a. an aqueous slurry of molybdenum trioxide;
b. a reducing agent selected from the group consisting of a finely
divided metal, sulfur, sulfur dioxide, hydrogen sulfide, hydrazine
hydrate, ammonia, hydroxylamine and an organic reducing agent
capable of reducing at least some of the molybdenum to a valence
state below +6 at ratio of from about 0.0001 to 0.2 moles of the
reducing agent per mole of molybdenum; and
c. antimony oxide in a ratio of from about 0.1 to 9 moles of
antimony oxide
promoted molybdenum. .Iaddend..Iadd. 11. The process of claim 10
wherein the finely divided metal in component (b) in the catalyst
preparation is selected from the group consisting of molybdenum,
tungsten, aluminum and nickel. .Iaddend..Iadd. 12. The process of
claim 11 wherein the finely divided metal in component (b) in the
catalyst preparation is molybdenum. .Iaddend..Iadd. 13. The process
of claim 11 wherein the catalyst is of the formula [Sb.sub.2
Mo.sub.3 O.sub.x +Mo.degree..sub.0.06 ]. .Iaddend. .Iadd. 14. The
process of claim 11 wherein the catalyst components are combined in
the following order:
a. molybdenum trioxide is reacted with the reducing agent; and
b. antimony trioxide is added to the reaction mixture of (a).
.Iaddend.
Description
This invention relates to a process for the catalytic oxidation of
olefins to unsaturated aldehydes and acids and to the oxidation of
olefin-ammonia mixtures to unsaturated nitriles. More specifically
this invention relates to a process for the catalytic oxidation of
olefins such as propylene and isobutylene to acrolein, acrylic
acid, methacrolein, and methacrylic acid, respectively, and the
ammoxidation of propylene and isobutylene, respectively, to
acrylonitrile and methacrylonitrile.
The catalyst of this invention is composed of the oxides of
molybdenum and antimony and preferably contains other metal oxides.
The catalyst compositions most useful in this invention are
represented by the following formula:
wherein A comprises one or more of the promoting elements selected
from the group consisting of tellurium, tungsten, titanium,
manganese, nickel, iron, copper, lead, rhenium, bismuth, tin,
uranium, chromium, phosphorus and boron, and B is a member selected
from the group consisting of molybdenum, tungsten, aluminum, nickel
and sulfur, and wherein a is a number of from 0.001 to 1.0, b is a
number of from 0 to 2.0 c is a number from 1 to 9, d is a number
from 1 to 9, and e is a number dependent upon the valence
requirements of the combined metals. The preferred catalysts
include those compositions wherein a is 0.005 to 0.5, b is 0.001 to
1.0, c is 1 to 8, d is 1 to 8 and e is 4 to 40.
The method employed in preparing the catalyst of this invention is
critical to the oxidation process described herein. In the
empirical formula designating the composition of the catalyst of
this invention, A in the formula represents a promoter element and
B represents a reducing element. The method employed in preparing
the catalyst departs from the usual classical procedures involving
co-precipitation or impregnation techniques and involves the simple
mixing of the respective metal oxides of antimony and molybdenum,
the reducing agent and the compound of the promoter element or
elements as a slurry in water.
In a preferred procedure for combining the essential elements of
the catalyst composition, an aqueous suspension of molybdenum
trioxide is pre-reduced in a controlled manner so that at least
some of the molybdenum is reduced to a valence state below +6
before the molybdenum oxide is mixed with a lower oxide of
antimony, antimony trioxide. A wide range of reducing agents can be
employed for this purpose including finely divided or colloidal
metals such as molybdenum, tungsten, magnesium, aluminum, nickel,
bismuth, antimony, chromium, cobalt, zinc, cadmium, tin, or iron,
sulfur, hydrogen sulfide, sulfur dioxide, hydrazine hydrate,
ammonia, hydroxylamine, organic reducing agents, such as, sugars,
pyrogallol, and the like. Most preferred is finely divided metal in
the amount of from about 0.01 to 0.2 atoms of metal per mole of
molybdenum trioxide present. It is also preferred that the promoter
element be added in a non-oxidizing form.
On refluxing the aqueous suspension of molybdenum trioxide with the
reducing agent, at least a part of the normally insoluble
molybdenum trioxide is solublized forming an intense deep blue
coloration. It is hypothesized that this blue color which develops
is the result of the reduction of molybdenum, at least in part, to
a lower oxidation state in the oxidation-reduction reaction
occurring between hexavalent molybdenum and the reducing metal.
Although preferredly the molybdenum trioxide is pre-reduced before
reaction with the antimony trioxide, beneficial results are also
obtained by first reacting the molybdenum trioxide with antimony
trioxide followed by reaction with the reducing agent, or by
reacting the three components simultaneously. It is also
contemplated to be within the scope of this invention to employ a
combination of a lower oxide of molybdenum with a higher oxide of
antimony, as for example antimony tetroxide or antimony pentoxide
in preparation of the catalyst.
Preferredly, the metal promoter of the catalyst is subsequently
added to the aqueous suspension of mixed oxides of antimony,
molybdenum and the reducing metal, in the form of a non-oxidizing
compound such as, for example, the metal oxide, hydrous metal
oxide, the hydroxide, the halide, the acid, a salt of the acid, a
salt of an organic acid, an organometallic compound and the like.
Satisfactory results are also obtained, however, by adding the
promoter element to the component mixture at any stage of the
catalyst preparation.
A highly reproducible method for combining the components of the
catalyst of this invention comprises refluxing an aqueous
suspension of molybdenum trioxide and a finely divided metal for a
period of about 1 to 3 hours at 100.degree. C. until the deep blue
coloration characteristic of a lower oxidation state of molybdenum
appears. Antimony trioxide is then added to the aqueous suspension
of the reduced molybdenum oxide and the reducing metal and this
mixture is again refluxed at 100.degree. C. for a period of about 1
to 5 hours. To this mixture is added the metal promoter in a form
disclosed hereinabove, and the entire mixture is further refluxed
for about 1 to 5 hours at the same temperature. The aqueous slurry
is then evaporated to dryness, and final drying is accomplished by
placing the catalyst in an oven at a temperature of about
120.degree. to 130.degree. C. for a period of from about 2 to 24
hours.
The catalyst of this invention may be supported on a carrier
material such as for example, silica, zirconia, calcium
stabilized-zirconia, titanis, alumina, thoria, silicon carbide,
clay, pumice, diatomaceous earth and the like, or it may be
employed satisfactorily in an unsupported form. If a carrier is
utilized it may be employed in amounts of up to 95 percent by
weight of the total catalyst composition.
The catalyst system herein described is useful in the oxidation of
olefins to corresponding oxygenated compounds, such as unsaturated
aldehydes and acids, and in the ammoxidation of olefins to
unsaturated nitriles. Nitriles and oxygenated compounds such as
aldehydes and acids can be produced simultaneously using process
conditions within the overlapping ranges for these reactions, as
set forth in detail below. The relative proportions of each that
are obtainable will depend on the catalyst and on the olefin
employed. It is also contemplated to be within the scope of this
invention, that with the catalyst system employed herein, the
unsaturated aldehyde may be further oxidized in a second step to
the corresponding unsaturated acid. The unsaturated aldehyde need
not be isolated from the other reaction products and can be further
oxidized to the unsaturated acid while remaining in the reaction
mixture. The term "oxidation" as used in this specification and
claims encompasses the oxidation to aldehydes and acids and to
nitriles, all of which conversions require oxygen as a
reactant.
Oxidation of Olefins to Aldehydes and Acids
The reactants used in the oxidation to obtain oxygenated compounds
are oxygen and an olefin such as propylene or isobutylene, or their
mixtures.
The olefins may be in admixture with paraffinic hydrocarbons, such
as ethane, propane, butane and pentane, as for example, a
propylene-propane mixture may constitute the feed. This makes it
possible to use ordinary refinery streams without special
preparation.
The temperature at which this oxidation is conducted may vary
considerably depending upon the catalyst, the particular olefin
being oxidized and the correlated conditions of the rate of
throughput or contact time and the ratio of olefin to oxygen. In
general, when operating at pressures near atmospheric, i.e., --10
to 100 p.s.i.g., temperatures in the range of 250.degree. to
600.degree. C. may be advantageously employed. However, the process
may be conducted at other pressures, and in the case where
superatmospheric pressures, e.g., above 100 p.s.i.g. are employed
somewhat lower temperatures are feasible. In the case where this
process is employed to convert propylene to acrolein and acrylic
acid, or isobutylene to methacrolein and methacrylic acid, a
temperature range of from about 300.degree. to 500.degree. C. has
been found to be optimum at atmospheric pressure.
While pressures other than atmospheric may be employed it is
generally preferred to operate at or near atmospheric pressure,
since the reaction proceeds well at such pressures and the use of
expensive high pressure equipment is avoided. Pressures of between
atmospheric and 30 p.s.i.g. are most preferred.
The apparent contact time employed in the process is not critical
and may be selected from a broad operable range which may vary from
0.1 to 50 seconds. The apparent contact time may be defined as the
length of time in seconds which the unit volume of gas measured
under the conditions of reaction is in contact with the apparent
unit volume of the catalyst. It may be calculated, for example,
from the apparent volume of the catalyst bed, the average
temperature and pressure of the reactor, and the flow rates of the
several components of the reaction mixture.
The optimum contact time will, of course, vary depending upon the
olefin being treated, but in the case of propylene and isobutylene
the preferred apparent contact time is 0.5 to 15 seconds.
A molar ratio of oxygen to olefin between about 0.5:1 to 10:1
generally gives the most satisfactory results. For the conversion
of propylene to acrolein, and isobutylene to methacrolein and
methacrylic acid, a preferred ratio of oxygen to olefin is from
about 1:1 to about 5:1. The oxygen used in the process may be
derived from any source; however, air is the least expensive source
of oxygen, and is preferred.
The addition of water to the reaction mixture has a marked
beneficial influence on the course of the reaction in that it
improves the conversion and the yield of the desired product.
Accordingly, we prefer to include water in the reaction mixture.
Generally, a ratio of olefin to water in the reaction mixture of
from 1:0.5 to 1:10 will give very satisfactory results, and a ratio
of from 1:1 to 1:6 has been found to be optimum when converting
propylene to acrolein and acrylic acid, and isobutylene to
methacrolein and methacrylic acid. The water, of course, will be in
the vapor phase during the reaction.
Inert diluents such as nitrogen and carbon dioxide may be present
in the reaction mixture.
Oxidation of Olefins to Nitriles
The reactants used are the same as those employed in the production
of aldehydes and acids above, plus ammonia. Any of the olefins
described can be used.
In its preferred aspect, the process comprises contacting a mixture
comprising propylene or isobutylene, ammonia and oxygen with the
catalyst at an elevated temperature and at atmospheric or near
atmospheric pressure.
Any source of oxygen may be employed in this process. For economic
reasons, however, it is preferred that air be employed as the
source of oxygen. From a purely technical viewpoint, relatively
pure molecular oxygen will give equivalent results. The molar ratio
of oxygen to the olefin in the feed to the reaction vessel should
be in the range of 0.5:1 to 10:1 and a ratio of about 1:1 to 5:1 is
preferred.
Low molecular weight saturated hydrocarbons do not appear to
influence the reaction to an appreciable degree, and these
materials can be present. Consequently, the addition of saturated
hydrocarbons to the feed to the reaction is contemplated within the
scope of this invention. Similarly diluents such as nitrogen and
the oxides of carbon may be present in the reaction mixture without
deleterous effect.
The molar ratio of ammonia to olefin in the feed to the reaction
may vary between about 0.05:1 to 5:1. There is no real upper limit
for the ammonia-olefin ratio, but there is generally no reason to
exceed the 5:1 ratio. At ammonia-olefin ratios appreciably less
than the stoichiometric ratio of 1:1, various amounts of oxygenated
derivates of the olefin will be formed.
Significant amounts of unsaturated aldehydes and even unsaturated
acids as well as nitriles will be obtained at ammonia-olefin ratios
substantially below 1:1, i.e., in the range of 0.15:1 to 0.75:1,
particularly in the case of higher olefins such as isobutylene.
Outside the upper limit of this range only insignificant amounts of
aldehydes and acids will be produced, and only small amounts of
nitriles will be produced at ammonia-olefin ratios below the lower
limit of this range. It is generally possible to recycle any
unreacted olefin and unconverted ammonia.
We have found that in many cases water in the mixture fed to the
reaction vessel improves the selectivity of the reaction and yield
of nitrile. However, reactions not including water in the feed are
not to be excluded from this invention, inasmuch as water is formed
in the course of the reaction. Sometimes it is desirable to add
some water to the reaction mixture, and in general, molar ratios of
added water to olefin, when water is added, on the order of 1:1 to
4:1 are particularly desirable. However higher ratios may be
employed, i.e., ratios of up to about 10:1 are feasible.
The reaction is carried out at a temperature within the range from
about 250.degree. to about 600.degree. C. The preferred temperature
range is from about 350.degree. to 500.degree. C.
The pressure at which the reaction is conducted is not critical,
and the reaction should be carried out at about atmospheric
pressure or pressures up to about 5 atmospheres. In general, high
pressures, i.e. about 15 atmospheres, are not suitable, since
higher pressures tend to favor the formation of undesirable
by-products.
The apparent contact time is an important variable, and contact
time in the range of from 0.1 to about 50 seconds may be employed.
The optimum contact time will, of course, vary, depending upon the
olefin being treated, but in general, a contact time of from 1 to
15 seconds is preferred.
In general, any apparatus of the type suitable for carrying out
oxidation reactions in the vapor phase may be employed in the
execution of this process. The processes may be conducted either
continuously or intermittently. The catalyst bed may be a fixed bed
employing a large particulate or pelleted catalyst, or in the
alternative, a so-called "fluidized" bed of catalyst may be
employed.
The reactor may be brought to the reaction temperature before or
after the introduction of the reaction feed mixture. However, in a
large scale operation, it is preferred to carry out the process in
a continuous manner, and in such a system the recirculation of the
unreacted olefin is contemplated. Periodic regeneration or
reactivation of the catalyst is also contemplated, and this may be
accomplished, for example, by contacting the catalyst with air at
an elevated temperature.
The products of the reaction may be recovered by any of the methods
known to those skilled in the art. One such method involves
scrubbing the effluent gases from the reactor with cold water or an
appropriate solvent to remove the products of the reaction. In the
recovery of nitrile products it may be desirable to employ
acidified water to absorb the products reaction and neutralize
unconverted ammonia. The ultimate recovery of the products may be
accomplished by conventional means, such as by distillation or
solvent extraction. The efficiency of the scrubbing operation may
be improved when water is employed as the scrubbing agent by adding
a suitable wetting agent to the water. Where molecular oxygen is
employed as the oxidizing agent in this process, the resulting
product mixture remaining after the removal of the aldehydes, acids
and nitriles may be treated to remove carbon dioxide with the
remainder of the mixture containing the unreacted olefin and oxygen
being recycled through the reactor. In the case where air is
employed as the oxidizing agent in lieu of molecular oxygen, the
residual product after separation of the nitriles and other
carbonyl products may be scrubbed with a non-polar solvent, e.g., a
hydrocarbon fraction, in order to recover unreacted olefin, and in
this case the remaining gases may be discarded. The addition of a
suitable inhibitor to prevent polymerization of the unsaturated
products during the recovery steps is also contemplated.
The following examples are representative of the process conditions
and catalyst compositions that are suitable for the process of this
invention, however, the scope of the invention is not to be limited
by these examples.
In the examples, the activity of the catalysts was determined using
a fixed-bed microreactor composed of a feed induction system, a
molten salt bath furnace, a scrubber and a vapor phase
chromatograph. The reactor was constructed from a 5 inches length
of pipe having a 3/8 inch I.D., and a catalyst capacity of
approximately 4 cc of catalyst.
The catalyst employed had a particle size of 20-32 mesh. The
reaction product obtained from the oxidation reaction was absorbed
in a water scrubber and the ammoxidation product was absorbed in a
water-hydrochloric acid scrubber solution. An aliquot of the
scrubber liquid was subsequently injected into a Hewlett and
Packard gas chromatograph Model No. 5750 for analysis. The
chromatograph contained a Porapak-Q column, 2 meters in length and
1/8 inch in diameter.
The column was maintained at a temperature of 180.degree. C. for
the analysis of acrolein, methacrolein, acrylonitrile,
methacrylonitrile and acetic acid, and at 230.degree. C. for the
analysis of acrylic acid and methacrylic acid. The unabsorbed
gaseous product, consisting essentially of carbon monoxide, carbon
dioxide, oxygen, nitrogen and unreacted hydrocarbon, was analyzed
by means of a Fisher Gas Partitioner. Hydrogen cyanide and ammonia
when present were determined by titration.
The reaction conditions employed and the conversions obtained
utilizing the various hydrocarbon feeds and catalyst compositions
described in the invention are summarized in Tables 1 to 5. In
these experiments, the results are reported as the mole percent per
pass conversion to the desired product which is defined as:
##EQU1## and selectivity on a molar basis is defined as:
##EQU2##
The catalysts employed in Examples 1 to 40 (Tables 2 to 5) were
prepared according to the following procedures:
EXAMPLE 1
64.8 Grams of molybdenum trioxide (MoO.sub.3) (0.45 gram atoms of
Mo) was slurried in water and heated at 100.degree. C. for one
hour. 43.7 Grams of antimony trioxide (Sb.sub.2 O.sub.3) (0.3 gram
atoms of Sb) was added to the aqueous slurry and refluxing was
continued for five hours at 110.degree. C. This was then stirred
constantly at room temperature for 16 hours. The bulk of the slurry
was then slowly evaporated to dryness, and the solid was then dried
at 130.degree. C. for 40 hours.
EXAMPLE 2
64.8 Grams of molybdenum trioxide (MoO.sub.3) (0.45 gram atoms of
Mo) were reacted with 0.864 grams of molybdenum metal powder (0.009
gram atoms of Mo) in about 300 cc of water. The aqueous slurry was
refluxed for about one hour with constant stirring. The color of
the slurry on completion of the reaction was blue. To this slurry
was added 43.7 grams of antimony trioxide (Sb.sub.2 O.sub.3) (0.3
gram atoms of Sb), and stirring at reflux temperatures was
continued at least for one additional hour. The color of the slurry
was dark green.
The promoted catalysts were prepared by adding the promoter element
to the slurry of Example 2 in the form of the compound and the
amount of the compound indicated in Table I. The slurry containing
the added promoter element was refluxed for 3 more hours with
continual stirring, was then placed in a large beaker and was
slowly evaporated to dryness over a hot plate. The solid was
finally dried in an oven at 130.degree. C. for about 24 hours.
TABLE I
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Reducing Element Example in place of Mo.degree. (grams) Promoter
Element Grams of Compound Used
__________________________________________________________________________
3 Al.sub.0.06 0.243 -- 4 Ni.sub.0.06 0.528 -- 5 S.sub.0.06 0.289 --
6 W.sub.0.06 1.655 -- 7 Mo.sub.0.06 0.864 Bi.sub.0.01 0.727
Bi(NO.sub.2).sub.2.5H.sub.2 O + HNO.sub.3 8 " " Bi.sub.0.1 6.61
Bi(C.sub.2 H.sub.3).sub.3 9 " " Bi.sub.0.1 7.27
Bi(NO.sub.3).sub.2.5H.sub.2 O 10 " " P.sub.0.01 0.173 H.sub.3
PO.sub.4 (85% soln.) 11 " " P.sub.0.1 1.73 H.sub.3 PO.sub.4 (85%
soln.) 12 " " P.sub.0.21 4.325 H.sub.3 PO.sub.4 (85% soln.) 13 " "
P.sub.0.5 8.647 H.sub.3 PO.sub.4 (85% soln.) 14 " " P.sub.1.0
17.299 H.sub.3 PO.sub.4 (85% soln.) 15 " " B.sub.0.01 0.093 H.sub.3
BO.sub.3 16 " " Te.sub.0.01 0.404 TeCl.sub.4 17 " " Te.sub.0.1
4.041 TeCl.sub.4 18 W.sub.0.06 1.655 Te.sub.0.1 4.041 TeCl.sub.4 19
W.sub.0.2 5.52 Te.sub.0.1 4.041 TeCl.sub.4 20 Mo.sub.0.06 0.864
W.sub.0.1 3.75 H.sub.2 WO.sub.4 21 " " Mn.sub.0.1 1.726 MnCO.sub.2
22 " " Ni.sub.0.1 1.781 NiCO.sub.2 23 " " Cu.sub.0.1 2.02
CuCl.sub.2 24 " " Pb.sub.0.1 5.69 Pb(C.sub.2 H.sub.3
O.sub.2).sub.2.3H.sub. 2 O 25 " " Re.sub.0.1 4.02 NH.sub.4
ReO.sub.4 26 " " Sn.sub.0.1 3.38 SnCl.sub.2.2H.sub.2 O 27 " "
Te.sub.0.1.Sn.sub.0.1 3.38 SnCl.sub.2.2H.sub.2 O 4.04 TeCl.sub.4 28
" " Cr.sub.0.1 1.50 CrO.sub.2 29 " " Ni.sub.0.1 1.78 NiCO.sub.2 30
" " Ti.sub.0.1 1.20 TiO.sub.2 31 " " W.sub.0.1 3.75 H.sub.2
WO.sub.4 32 " " Fe.sub.0.05 2.02 FeCl.sub.2 33 " " Te.sub.0.1
Fe.sub.0.05 4.04 TeCl.sub.4.2.02 FeCl.sub.2 34 " " U.sub.1 137 g
heat treated USb.sub.2 O.sub.10 35 " " P.sub.0.1 1.73 H.sub.3
PO.sub.4 (85% soln.) 36 " " Te.sub.0.1 4.041 TeCl.sub.4 37 " " --
same as in Example 2 38 " " Te.sub.0.1 4.041 TeCl.sub.4 39 " " --
same as in Example 2 40 " " P.sub.0.1 1.73 g H.sub.3 PO.sub.4 (85%
__________________________________________________________________________
soln.)
The effectiveness of the catalyst of this invention for the
conversion of olefins to the corresponding unsaturated aldehydes,
acids and nitriles is demonstrated by the conversion of isobutylene
to methacrolein, methacrylic acid and methacrylonitrile, and
propylene to acrolein, and acrylic acid shown in the examples in
Tables 2 to 5. The examples in Table 2 illustrate the improvement
obtained in the conversion of isobutylene to methacrolein with the
promoted, reduced, antimony-molybdenum catalysts as compared with
the unpromoted catalysts for this same reaction. The data in this
Table also show the effect of varying the concentration of the
promoter, the use of more than one promoter in the catalyst, and
the effect of varying the reaction conditions such as the inclusion
of water in the feed. The examples given in Tables 3 to 5 show the
effect of these catalysts for the oxidation of other feeds such as
propylene and methacrolein to acrolein and methacrylic acid,
respectively, and the ammoxidation of isobutylene to
methacrylonitrile.
TABLE II
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Oxidation of Isobutylene to Methacrolein Reaction Conditions Molar
Feed Ratio, IC.sub.4.sup.= /air 1/20 Contact Time 3 seconds
Temperature, .degree.C. = 371 Mole Percent Conversion to: Mole
Percent Methacrylic Selectivity to Example Catalyst Methacrolein
Acid Methacrolein
__________________________________________________________________________
1 Sb.sub.2 Mo.sub.3 O.sub.x 35.6 -- 57 2 Sb.sub.2 Mo.sub.3 O.sub.x
+ Mo.sub.0.06 .degree. 37.9 3.0 61 3 Sb.sub.2 Mo.sub.3 O.sub.x +
Al.sub.0.06 .degree. 44.2 1.2 54 4 Sb.sub.2 Mo.sub.3 O.sub.x +
Ni.sub.0.06 .degree. 43.9 1.0 59 5 Sb.sub.2 Mo.sub.3 O.sub.x +
S.sub.0.04 .degree. 42.9 2.9 65 6 Sb.sub.2 Mo.sub.3 O.sub.x +
W.sub.0.06 37.6 4.4 42 7 Bi.sub.0.01 [Sb.sub.2 Mo.sub.3 O.sub.x +
Mo.sub.0.06 .degree.] tr tr -- (HNO.sub.3 was used during the
preparation) 8 Bi.sub.0.1 [Sb.sub.2 MoO.sub.x O.sub.x + Mo.sub.0.06
44.2ree.] tr 62 9 Bi.sub.0.1 [Sb.sub.2 Mo.sub.3 O.sub.x +
Mo.sub.0.04 .degree.] 53.4 1.9 63 (Nitrate free) 10 P.sub.0.01
[Sb.sub.2 Mo.sub.3 O.sub.x + Mo.sub.0.06 .degree.] 48.4 1.8 57 11
P.sub.0.1 [Sb.sub.2 Mo.sub.3 O.sub.x + Mo.sub.0.06 .degree.] 30.3
12.1 42 12 P.sub.0.25 [Sb.sub.2 Mo.sub.3 O.sub.x + Mo.sub.0.06
.degree.] 17.6 tr 68 13 P.sub.0.5 [Sb.sub.2 Mo.sub.3 O.sub.x +
Mo.sub.0.06 .degree.] 19.9 0.5 50 14 P.sub.1.0 [Sb.sub.2 Mo.sub.3
O.sub.x + Mo.sub.0.06 .degree.] 6.8 0.3 30 15 B.sub.0.01 [Sb.sub.2
Mo.sub.3 O.sub.x + Mo.sub.0.06 .degree.] 57.2 2.2 60 16 Te.sub.0.01
[Sb.sub.2 Mo.sub.3 O.sub.x + Mo.sub.0.06 .degree.] 63.5 -- 80 17
Te.sub.0.1 [Sb.sub.2 Mo.sub.3 O.sub.x + Mo.sub.0.06 .degree.] 71.7
-- 77 18 Te.sub.0.1 [Sb.sub.2 Mo.sub.3 O.sub.x + W.sub.0.06
.degree.] 62.2 7.2 74 19 Te.sub.0.1 [Sb.sub.2 Mo.sub.3 O.sub.x +
W.sub.0.2 .degree.] 49.1 5.1 55 20 W.sub.0.1 [Sb.sub.2 Mo.sub.3
O.sub.x + Mo.sub.0.06 .degree.] 58.2 -- 60 21 Mn.sub.0.1 [Sb.sub.2
Mo.sub.3 O.sub.x + Mo.sub.0.06 .degree.] 56.5 0.3 74 22 Ni.sub.0.1
[Sb.sub.2 Mo.sub.3 O.sub.x + Mo.sub.0.06 .degree.] 56.5 0.7 70 23
Cu.sub.0.1 [Sb.sub.2 Mo.sub.3 O.sub.x + Mo.sub.0.06 .degree.] 56.4
-- 70 24 Pb.sub.0.1 [Sb.sub.2 Mo.sub.3 O.sub.x + Mo.sub.0.06
.degree.] 55.5 1.2 69 25 Re.sub.0.1 [Sb.sub.2 Mo.sub.3 O.sub.x +
Mo.sub.0.06 .degree.] 46.1 -- 48 26 Sn.sub.0.1 [Sb.sub.2 Mo.sub.3
O.sub.x + Mo.sub.0.06 .degree.] 42.4 6.4 53 27 Te.sub.0.1
Sn.sub.0.1 [Sb.sub.2 Mo.sub.3 O.sub. x + Mo.sub.0.06 .degree.] 77.9
-- 85 28 Cr.sub.0.1 [Sb.sub.2 Mo.sub.3 O.sub.x + Mo.sub.0.06
.degree.] 41.2 tr 52 *29 Ni.sub.0.1 [Sb.sub.2 Mo.sub.3 O.sub.x +
Mo.sub.0.06 .degree.] 62.5 1.3 73 *30 Ti.sub.0.1 [Sb.sub.2 Mo.sub.3
O.sub.x + Mo.sub.0.06 .degree.] 61.2 3.9 70 *31 W.sub.0.1 [Sb.sub.2
Mo.sub.3 O.sub.x + Mo.sub.0.06 .degree.] 60.6 3.8 70 32 Fe.sub.0.5
[Sb.sub.2 Mo.sub.3 O.sub.x + Mo.sub.0.06 .degree.] 41.4 tr 46 33
Te.sub.0.1 Fe.sub.0.05 [Sb.sub.2 Mo.sub.3 O.sub.x + Mo.sub.0.06
.degree.] 60.1 34 U.sub.1 [Sb.sub.4.67 Mo.sub.2.3 + Mo.sub.0.06 ]
55.0 4.3 59
__________________________________________________________________________
*Molar Feed ratio, IC.sub.4.sup.= /air/H.sub.2 O = 1/11/4 Reaction
Temp., .degree.C. = 399
TABLE III
__________________________________________________________________________
Oxidation of Propylene to Acrolein Reaction Conditions Molar Feed
Ratio, C.sub.3.sup.= /air = 1/20 Reaction Mole Percent Temp. C.T.
Mole Percent Conversion to: Selectivity to Example Catalyst
(.degree.C.) (Secs) Acrolein Acrylic Acid Acrolein
__________________________________________________________________________
35 P.sub.0.1 [Sb.sub.2 Mo.sub.3 O.sub.x + Mo.sub.0.06 .degree.] 400
3.0 20.7 -- 66 36 Te.sub.0.1 [Sb.sub.2 Mo.sub.3 O.sub.x +
Mo.sub.0.06 .degree.] 450 5.0 42.5 7.9 84
__________________________________________________________________________
TABLE IV
__________________________________________________________________________
Ammoxidation of Isobutylene to Methacrylonitrile Reaction
Conditions Molar Feed Ratio, IC.sub.4.sup.= /NH.sub.3 /air =
1/1.5/20 Contact time = 3 seconds.sup.2 Temperature, .degree.C. =
399 Mole Percent Conversion to: Mole Percent Acrolein &
Selectivity to Example Catalyst Methacrylonitrile Methacrolein
Methacrylonitrile
__________________________________________________________________________
37 [Sb.sub.2 Mo.sub.3 O.sub.x + Mo.sub.0.06 .degree.] 42.5 1.9 43
38 Te.sub.0.1 [Sb.sub.2 Mo.sub.3 O.sub.x + Mo.sub.0.06 .degree.]
71.1 3.5 73
__________________________________________________________________________
TABLE V
__________________________________________________________________________
Oxidation of Methacrolein to Methacrylic Acid Reaction Conditions
Molar Feed Ratio, Methacrolein/Air/H.sub.2 O = 1/6/5 Contact Time,
sec. = 1.0 Temperature, .degree.C. = 400 Mole Percent conversion
to: Mole Selectivity to Example Catalyst Methacrylic Acid
Methacrylic Acid
__________________________________________________________________________
39 [Sb.sub.2 Mo.sub.3 O.sub.x + Mo.sub.0.06 .degree.] 11.9 57 40
P.sub.0.1 [Sb.sub.2 Mo.sub.3 O.sub.x + Mo.sub.0.06 .degree.] 25.6
53
__________________________________________________________________________
* * * * *